1. Field of the Disclosure
The instant disclosure relates to a temperature measurement component embedded hot runner nozzle structure; in particular, to a hot runner nozzle structure for transferring molten plastics from the injection nozzle to the mold cavity through the hot runners and related plastic mold injection structures.
2. Description of Related Art
Runners or flow channels mainly serves to transfer molten plastics which are emitted from the nozzle to the mold cavity. The quality of the flow channels directly affects the overall plastic properties, product appearance, precision of dimensions, and molding cycle. Since designers often delegate the quality portion of the work to the molding factory, quality control becomes difficult to manage.
Typical runners are generally categorized as hot and cold runners. A hot runner provides a channel for plastic materials to enter from the injection molding machine to the mold gate. After the plastic product has been ejected for each injection, the plastic materials remaining in the flow channel, which are not solidified, are not bound to be purged. Specifically, hot runner is suitable for manufacturing thin components and large scale plastic components such as liner board for vehicles, and housing for large size LCD televisions. Hot runner is known best for its small flow resistance and small pressure lost, which facilitates molding.
The main difference between hot runner and cold runner is the injection molding process. In general, temperature control is appropriately applied such that plastics in the flow channels or runners remain in a molten state, different from the molten plastics in the mold cavity which will eventually solidify, which prevent the casting system from cold slugging. As a result, no excess materials are generated. Since the plastics in the flow channel are not solidified, the injection flow in the flow channel remains smooth for the next injection. In order to keep a smooth flow, temperature control for the hot runner requires highly sensitive. Conventional runners are equipped with automatic heat adjustment controls as well as insulating means to prevent heat loss, clogging in the hot runner nozzle, and to ensure the flow properties of the plastics.
In terms of temperature control of hot runners in conventional arts, temperature measurements for the temperature of the molten plastics inside the hot runner are generally acknowledged as the temperature of the hot runner's main body at thermal equilibrium. Then, temperature is controlled accordingly, which is considered as an indirect temperature measurement. However, the aforementioned method does not reflect the actual temperature changes of the molten plastics within runners, nor provides information regarding the thermal stability among various regions. Consequently, the temperature displayed on temperature control varies from the actual temperature of the injection molten plastics, rendering the situation where the control temperature displaying normal temperature, yet the injection plastics are insufficiently heated or overheat (thermal cracking or pyrolysis). As a result, delays occur due to machine adjustments and time is consumed to track the root cause of the molding anomalies.
To address the above issues, the inventor strives via associated experience and research to present the instant disclosure, which can effectively improve the limitation described above.